Blackberry Z10 Calendar

I've a problem with Blackberry Z10 Calendar Appointments and Meetings. I've syncronized with my account on outlook.com (but it's the same thing on my local outlook on the pc).

If I enter an appointments on my BBZ10 I see it into te outlook.com calendar but after a few minutes it disappier from the BBZ10 calendar week and day! Even I see in the month view the color in that day.

Same thing if I enter an appointment on the outlook.com: I see it for a few minutes on my BBZ10 and then it disappears!

I think that ins't a problem of syncronitazion: the appointments and meetings are saved in the BBZ10 calendar (in the month view I can see the coloured days, only the colour but nont the appointments) but I cannot see them.